1. Technical Field
This invention relates to implantable defibrillators that have been developed to sense and control ventricular fibrillation which if not treated promptly would lead to sudden death.
2. Description of the Prior Art
Prior art implantable defibrillators are presently used in patients that have had an episode of ventricular fibrillation or hemodynamically unstable ventricular tachycardia.
Prior art implantable defibrillators consist of a pulse charge generator and a pair of electrodes, one of which is incorporated into an intravascular catheter placed in the superior vena cava at the level of the right atrial junction. The other electrode takes the form of a rectangular patch that covers the apex of the heart. The electrode also acts as a sensor to detect the onset of ventricular tachyarrhythmias.
Other prior art devices have shown the introduction of electrodes into the heart for pacing and monitoring the same. See for example U.S. Pat. Nos. 4,289,138 and 3,865,118.
In U.S. Pat. No. 4,289,138 an electrode assembly is shown for use with a catheter to be implanted within the heart. The electrodes are formed on the free ends of wires of different lengths rather than the prior known closed loop.
U.S. Pat. No. 3,865,118 discloses a transvenous coaxial catheter which is passed through a single channel to the heart. The catheter provides at least two insulated spacially adjustable electrical conductors. The device is used to pace the heart.
Applicant's device utilizes prior art implantable defibrillator pulse charge generator and detection technology present available with a new and novel internally deployed collapsible electrode patch that can be positioned on the epicardial surface by maneuvering a catheter through the chest wall to the heart and deploying the collapsed electrode, which on deployment regains its original shape.